Rats offer hope on Parkinson's disease

SCIENTISTS say they have been able to reverse the effects of Parkinson's disease in laboratory rats by transplanting tissue from the rodents' necks into their brains.

The findings, reported in yesterday's edition of the medical journal Neuron, need to be confirmed and the scope of the work expanded before it is applied to humans.

The rats were tested only for three months and the researchers from the University of Seville in Spain used a chemically induced model of Parkinson's disease that may have important differences from the condition that strikes human beings.

Their work is expected to open avenues to explore in the treatment of a disease that is at present incurable and which causes debilitating weakness, stiffness and muscle tremors. Doctors have tried to treat Parkinson's by stimulating the production of dopamine, a brain chemical, by injecting either a drug or dopamine-producing cells from foetal brain tissue. The drug's potency wanes and has serious side effects; the large number of fetal brain cells needed makes that method impractical as a routine treatment.

But the researchers, headed by Emilio F Espejo, turned to small nodules in the neck, known as carotid bodies, that usually measure oxygen and carbon dioxide levels in the blood. When starved of oxygen, the cells start pumping out dopamine. Tissue transplanted into the brain is also starved of oxygen.

Emilio Espejo and his colleagues wanted to see if carotid body tissue transplanted into the brain could supply the missing dopamine. They injected carotid body cells into the brains of the afflicted rats. The rats who received the transplants showed obvious improvement 10 days after surgery and kept improving.

"Most behavioural parameters recovered completely within the first month of grafting and remained stable, or even improved, throughout the study," the researchers reported.

In a commentary in the medical journal, Arnon Rosenthal of Genentech Inc, cautioned that many more questions need to be answered before the treatment is tried in humans. "Carotid body transplants have been tried before but with less success," he said. The difference may be the way the Espejo team prepared the cells.

- Reuters, Boston